Soil Flashcards
diffrence between soil and rock
separate soil using water only
hard granular
grains of hard rock materials espically silicates
soft granular
coral, shell, skeletal, fragments and volcanic ash
clay materials
small crystalline material, plate shapred particles
plate-like particles, negative charges on the outside, interacts with water, sweels and shrinks, gives soil plasticity
plant resdidue
peat, vegetation, organic matter
Equation for porosity
Vv / Vt
Vt = total volume of solid, water, sand Vv = water and air
equation for void ratio
Vv / Vs
Vs = solids Vv = water and air
Denisty
mass / volume
strength of soil
compression = good tension = not so goos shear = varies
2 shear strength parameters
- friction and cohension
fiction
effect on strength increasing with depth
cohension
soil moisture, plasticity, transient
soil and compaction
if you compact the soil when it improves it for construction
( density control = drives the air out)
what is rammed earth made up of
70% sand
30% clay
- check the denisty and water content
Advantage of earth construction
low cost easy to build easy to repair environmetally sustainable thermall mass
disadvantage of earth construction
water weathering erosion material availbility shape / form earthquake resistance
environmental impact of earth construction
low fossil fuel demand
low transport demand
highly recyclability and durable
good thermal mass
advantage of rammed earth
thermal mass residue and noise control strength durability low thermal fireproofing
rammed earth construction
roof overhang - keeps it dry
concrete beam to support floor slabs - stable connection
start walls above grade - splash protection
optional side drain
a solid foundation - rammed earth walls are heavy
what is rammed earth made environmentally?
70-80% sand = fine gravel
20-30% clay = not too plastic
5-10% cement = optional
compacted well
vernacular and residue methods
vernacular = loess, adobe, troglodites innovation = rammed, stabilised earth
what is adobe
loess good band material
silt and clay size (10-25%)
high void ratio, cemented and collapsible
wetted collapsed loess materials
reformed and dried
bricks and plaster
how to make adobe
make adobe right soil
wet it, mix it, dry it
build bricks, walls and plaster
what is cob
lump and rounded mass
what is soil made off?
1-2 parts clay 1 part silt 2-3 parts sand 3-4 gravel plus some straw (3-5%)
layers rammed together by hand making thick walls
